G ehmann



March 28, 1961 L. G. EHMANN Re. 24,958

LIFT TRUCK WITH SINGLE TELESCOPIC MAST Original Filed Sept. 30. 1954SSheQtS-Sheet 1 FIG. I

LESLIE G. EHM ANN y WWW A TTORNEVS' 8 5 2 ou t m 2 S nOmN a .r TN R a mmM WM 5 s 1... wn m... a M c E m I U H m a 5 m L m 6 HM m .5 s L m W 4 U5.mw Tl mw m m 9 Q 1 d u 2 m h a 3 m m. g M F 0 28, GHEHMANN Re.

LIFT TRUCK WITH SINGLE TELESCOPIC MAST Original Filed Sept. 30. 1954 5Sheets-Sheet 3 INVENTOR. LESLIE G. EHMANN g mmam ATTORNEY:

March 28, 1961 s. EHMANN LIFT TRUCK WITH SINGLE T ELESCOPIC MAST FiledSept. 50. 1954 5 Sheets-Sheet 4 Original FIG.6

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5 U U m fi w L W W H G 7 m l I I x F G 9 l R 5 7 F a/ 4 -uu .nnnunuNu In il flfl M /////////A2 8 0 l ll BY WM? MM ATTORNEYS March 28, 1961 1..G. EHMANN LIFT TRUCK WITH SINGLE TELESCOPIC MAST 5 Sheets-Shet 5Original Filed Sept. 30. 1954 u m 7 2 3 O O 7 I l 9 O A, m m 2 2 d M 27y fix m l w 5 2 a/iFfl mm llll, 2 22%0 a d O O 1 u o O O [I O 7 u 2 FIG.IO

ooooooi ATTORNEYS Re. 24,958 Reiasuecl Mar. 28, 1961 ice .LIFI' TRUCKWITH SINGLE TELESCOPIC MAST Leslie G. Ehmann, Portland, Oreg.,assi'gnor, by mesne assignments, to Hyster Company, a corporation ofNevada Original No. 2,915,210, dated Dec. 1, 1959, Ser. No. 459,492,Sept. 30, 1954. Application for reissue Sept. 30, 1960, Ser. No. 60,282

Claims. (Cl. 214674) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

This invention relates to industrial lift trucks, and particularly toimprovements in the load elevating mechanism of such a truck.

The visibility of the driver of the conventional lift truck isconsiderably impaired by the load. elevating mechanism thereof, which ismounted at the forward end of the truck. This load elevating mechanismprojects upwardly to a level usually above that of the eye.

' elevating ram, which is operatively connected to the inner upright,and operatively connected by means of a chain and sheave arrangement toa load carriage, the latter usually having rollers having a rolling,guided fit with the channels of the inner upright.

When maneuvering the conventional lift truck into a position to bringthe lift forks or other load engaging mechanism into register with aload in the process of picking it up, or into register with a depositstation or location when depositing a load, the driver has to peeraround the upright channels, or through the openings between the ram andthe elevating'chain or chains, or through the openings between thechains and the upright channels, in order to bring the truck or the tipsof the lift forks to the desired position. Also, the driver has similardilficulty when operating the truck in confined quarters or along narrowaisles. Such poor visibility causes slow truck operation, damage togoods or articles being handled because of their being bumped againstobjects along the path of travel of the truck, and also causes damage toobjects along the path which are bumped during operation of the truck.

'Although many attempts have been made to improve the visibility of thedriver of the conventional lift truck, the above-described loadelevating mechanism has not, up to the present time, been substantiallyaltered.

It is a main object of the present. invention to provide 'a lift truckin which the upright structure is so constructed I that the visibilityof the operator or driver of the truck is increased to a remarkableextent to thus enable faster handling of goods and provide increasedsafety of operation.

A more particular object of the present invention is to provide a lifttruck having an upright or mast structure and an elevating ram arrangedin an extremely compact unit at the forward end of the truck, to affordgreatly increased visibility for the driver of the truck over thatafforded by previous trucks.

Another object of the present invention is to provide a lift truckhaving the load carriage mounted on and movable along the outer upright,instead of the inner upright, to permit the uprights to be formed in amore compact unit than previously has been'possible.

Another object of the present invention is to provide a lift truckwherein the inner and outer uprights comprise single, telescopicallyrelated members of tubular form having small diameters as compared tothe lateral dimensions of the conventional channel uprights.

Another object of the present invention is to provide an upright'unitconstructed to have substantially greater resistance to side loadingstresses than conventional units, to enable it to operate successfullyin side loading operations.

A furtherobject of the present invention is to provide a truck of thecharacter above described wherein the load carriage may be elevatedwithout extension of the mast or upright structure.

A still further object of the present invention is to provide animproved load elevating mechanism attachment for a lift truck.

Another object of the present invention is to provide a lift truckhaving a simple and inexpensive load elevating mechanism and, inparticular, one wherein the load carriage is formed to permit a load tobe supported at a place close to the front axle of the truck despite aconsiderable forward disposition of the upright structure.

Various other objects of the present invention will be apparent from thefollowing description taken in connection with the accompanyingdrawings, wherein:

Fig. 1 is a somewhat schematic, right-hand, side elevational view of alift truck incorporating the concepts of the present invention, showingthe load elevating mechanism in its extended position;

Fig. 2 is a front, right perspective view of the truck in Fig. 1,showing the load elevating mechanism in its lowered position;

Fig. 3 is an enlarged, fragmentary side view in elevation taken from theleft-hand side of the truck, the load carriage being shown in apartially elevated condition, the left front wheel being shown removedand the axle assembly being shown in section;

Fig. 4 is a fragmentary view in horizontal section taken along line 44of Fig. 3;

Fig. 5 is a fragmentary, front elevational view of the lift truck, theload carriage being removed for convenience in illustration;

Fig. 6 is a sectional view taken along line 66 of Fig. 4; v

Fig. 7 is an enlarged horizontal section taken along line 77 of Fig. 6,more fully showing the manner of guiding and mounting the chain sheave;

Fig, 8 is an enlarged fragmentary section taken along line 8-8 of Fig.6;

Fig. 9 is a view similar to the upper portion of the view in Fig. 6, butshowing the elevating ram in its fully collapsed or telescoped position;

Fig. 10 is a view generally similar to Fig. 4, but showing a modifiedform of the invention;

Fig. 11 is a view similar to Fig. 9, but showing another modified formof the invention; and

Fig. 12 is a view generally similar to Fig. 4, but showing still anothermodified form of the invention.

Referring to the accompanying drawings wherein similar referencecharacters designate similar parts throughout, a lift truckincorporating the concepts of the present invention is disclosed. It ispointed out that the present invention is concerned with the loadelevating mechanism of the truck, and thus the. particular truck shown,apart from the elevating mechanism, is merely illustrative of the typeof truckon which theelevating mechanism may be mounted.

In Fig. 1, the lift truck is shown as including a body 9 supported by apair of front wheels 11 and a single difigible rear wheel 13. A driversseat 15 is mounted on the body and faces forwardly. Mounted on the frontof the truck is a load elevating mechanism including a mast or uprightsupport or base 17 on which is mounted an upright or mast structure.This upright or mast structure includes an inner tubular or hollowcolumnar upright or mast 18 and a telescopically related, outer tubularor hollow columnar upright or mast 19 which fits over the innerupright.Mounted for movement along the outer upright 19 is a load carriage 20.

Referring particularly to Figs. 3, 4 and 5, the mast or upright support17 is shown as assuming the form of a flat, heavy plate arranged betweenthe front wheels 11 and on which the inner upright 18 is welded orotherwise fixedly secured. Fixed to support 17 in spaced-apart, parallelrelation is a pair of upstanding bracket arms 21 and 22, which arejournaled, such as by split bearings 24, on the front axle 25 of thetruck (-see Fig. 3). It will be obvious to those skilled in the art thatarms 21 and 22 could be journaled on the truck in other ways tha theparticular way shown. I

An upstanding crosspiece 23 fits between arms 19 and 21 and is rigidlysecured to the arms and also rigidly secured to support 17. Crosspiece23 extends just back of the inner upright 18 (see Fig. -6) and is weldedto said inner upright. The rear wall of outer upright 18 is cut away atthe lower end thereof at 41 (see Fig. 3) to accommodate crosspiece 23.The upright support could be variously otherwise formed than in theparticular manner above described, as will readily occur to thoseskilled in the art.

The upright support 17 may be tilted about axle 25 by the operation of apair of hydraulic rams 27, the cylinders of which are pivotally mountedat 29 on the body of the truck, and the piston rods of which arepivotally connected at 31 to the upper ends of said arms. It is apparentthat the support may be tilted by means other than that specificallyshown.

Inner and outer uprights 18 and 19 are noncircular in cross section andpreferably are of rectangular cross-sectional configuration, as shown.Thus, the uprights are prevented because of their operatively related,opposed flat surface portions, from rotation relative to one an otherabout their longitudinal axes. In effect, such flat sides provide a nonrotatable connection between the uprights. Other ways of non-rotatablyconnecting the uprights to one another will readily occur to thoseskilled in the art.

As is best shown in Figs. 2, 4 and 5, the tubular uprights have smalllateral dimensions relative to the lateral dimension of the truck toprovide for remarkably increased visibility for the driver of the truckover that afforded by conventional trucks.

The uprights are shown as being-substantially coextensive in length, thelower ends of the outer upright, in the collapsed position of theupright or mast structure, terminating just short of base 17, and theupper end of the outer upright terminating just beyond the upper end ofthe inner upright and being closed by an end plate 45. The upper end ofthe inner upright is open, as disclosed in Fig. 6.

Arranged within the inner upright 18 is a hydraulic elevating ramincluding a cylinder 51 and a plunger 53. Cylinder 51 is mounted at itslower end, such as by a socket connection at 54, on base 17 at alocation somewhat forwardly of the central axis of the inner upright,for a reason to presently appear. adapted to be supplied to and relievedfrom cylinder 51 by means of a conduit at 56, which extends throughcrosspiece 23 and the rear wall of inner upright 18 (see Fig. 6).

gular, generally vertically elongated frame 55 (see Fig. 8).

Projecting through the opening in frame 55 is a sheave 57, the sheavehaving a shaft 59 rotatably extending through the sides of the frame 55(see Fig. 7). The shaft is shown as being located somewhat forwardly ofthe center line of plunger 53 for a reason to presently appear.

Shaft 59 of sheave 57 projects beyond the side walls of frame 55 (seeFig. 7) and each end of the shaft is guided for vertical movement by apair of vertically extending guides 71. These guides are secured inspaced relation to the inner faces of the side walls of the innerupright.

Frame 55 has a guide pin 73 fixed to the top portion thereof. When theplunger 53'is elevated, the pin is moved into a mating hole 75 (see Fig.9) formed in top plate in vertical alignment with pin 73. Guides 71,above mentioned, function to guide pin 73 into hole 75.

Sheave 57 has a diameter such that its forward peripheral edge orportion projects through a pair of vertical slots 61 and .63 formedrespectively in the front walls of inner upright 18 and outer upright 19(see Fig. 6). Because of the offest location of the hydraulic elevatingram relative to the inner upright and the offset location of shaft 59relative to plunger 53, the rear peripheral portion of the sheave isdisposed in spaced relation to the inner face of the rear wall of theinnerupright. It is, therefore, apparent that the forward reach orlength of an elevating chain 77, which is trained over sheave 57, isdisposed just forwardly of the front face of the front Wall of the outerupright 19, whereas the rear length or reach of said chain is locatedwithin the inner upright and is anchored at 79 to the upper end ofcylinder 51. Elevating chain 77 is anchored at 81 to load carriage 20.

The particular load carriage shown is merely illustrative of the typethat could be employed, and the following details are given merely byway of furnishing a full explanation of the particular embodiment of theinvention shown.

The load carriage shown includes a rigid, open rectangular frame whichcomprises a top horizontal bar 91, side bars 93 and 95, and a bottommember 97. Bottom member 97 is shown as comprising a rearwardly facingchannel (see Fig. 6) which has the rear margins of its flanges taperingor converging inwardly, as the parts are depicted in Fig. 4, to mergeinto straight central edge portions. As shown in Fig. 6, the connectionat 81 be tween the lower end of chain 77 and channel member 97 is at thetop upper flange of said channel member.

The load carriage-also includes a pair of spaced-apart, parallel, rollersupporting plates indicated by the reference numeral 20. Plates 20 arenotched at their forward edges at (see Fig. 6) to fit against the rearand bottom faces of top bar 91, to which faces they are secured bywelds. are also notched at 107 to fit against the upper face of channelmember 97 and to depend along the back of said channel member. Theroller supporting plates are connected by welds at notches 107 tochannel member 97.

A gusset plate 111 (see Fig. 4) connects each roller sup porting plateto bar 91.

Referring to Figs. 3, 4 and 6, mounted betweenrearwardly projectingportions of the roller supporting plates is a back roller 117, whichrides against the rear face of the outer upright. Rotatably mounted oneach roller supporting plate forwardly of roller 117 is a pair of sideThe forward edges of the roller supporting plates spacing of insertplates 125 and their location is the same as that of roller supportingplates 20, and the insert plates are welded at their rear edges to theforward edges of said roller supporting plates, as best shown in Fig. 6.

The provision of rollers at the four flat sides of the outer uprightprovides a nonrotatable connection between the carriage and the outerupright.

Supported by each roller supporting plate and the adjacent side bar ofthe carriage is a fork supporting rod 131 (see Fig. 1) which slidablyextends through the upper end of a fork 135 of conventionalconstruction. The back sides of the vertical portions of the forks restat the lower portions thereof against the front face of channel member97. The forks may be held in any position of lateral adjustment alongthe rods by any conventional retaining devices (not shown) and which areof no particular concern to the present invention.

A modified form of the invention is disclosed in Fig. 10, in which theelevating mechanism disclosed includes a hydraulic ram at 51, 53arranged within an inner tubular upright 201. Telescoped over innertubular upright 201 is an outer tubular upright 203. Tubular uprights201 and 203 are shown as being circular in cross section but areprevented from rotation relative to one another about their longitudinalaxes by keys 205, which are fixed within mating grooves formed in theouter surface of inner upright 2 01 and are slidably received withinmating grooves formed in the inner surface of the outer tubular upright203. Thus, keys 205 and their keyways may be considered as rendering thetubular uprights 201 and 203 noncircular in cross section.

Fixed to the opposite sides of outer tubular upright 203 is a pair ofguide strips 207 which extend substantially from the top to the bottomof the outer upright. A load carriage, indicated by the referencenumerals 20, 91 and 111, is movable along the outer upright 203 andcarries two pairs of rollers 209 for each strip 207. The pairs ofrollers for each strip are arranged one above the other, with therollers of each pair being disposed one on either side of the strip.Rollers 209 cooperating with strips 207 provide a nonrotatableconnection between the load carriage and the outer upright.

The uprights 201 and 203 are tiltably mounted on a lift truck, only thefront portion of which is shown, in the same manner as is the uprightstructure of the first form of the invention.

Fig. 11 shows another modified form of the invention in which the sheaveframe 55 is fixedly connected to the top piece 45 of the outer upright19. The construction of the upper end of the elevating mechanism, apartfrom the difference above explained, is very similar to that of thefirst form of the invention. However, no guide pin 73 is employed and noguides 71 for shaft 59 are required. In this form of the invention thedimensions of the parts are such that, when the hydraulic elevating ramis in its fully collapsed position, the uprights will be in their fullytelescoped positions and the load carriage will be at its lowermostposition on the outer upright 19. The inven tion is not intended to belimited to a construction where the sheave is bodily fixed to the upperend of plunger 53, when the truck is of the general type disclosed inFig. 11, because the sheave could instead be mounted on the outeruptight.

The operation of the form of the lift truck in Fig. 11 is as follows.Since frame 55 is fixed to outer upright 19, any movement of plunger 53causes a corresponding movement of the outer upright. Because of thechain and sheave arrangement provided, the load carriage will move twiceas fast as the outer upright. Thus, any movement of the plunger willcause movement of both the outer upright and the load carriage.

In the first form of p the invention, however, the plunger. 53 may moveupwardly from the position shown in Fig. 9 to the position shown in Fig.6 without causing any movement of the outer upright 19. Therefore, the

load carriage will be moved upwardly from the position shown in Fig. 1to the position shown in Fig. 6, which is a distance twice that whichthe plunger 53 moves. This movement of the load carriage withoutextension of the upright structure is known as free lift. Therefore, thetruck of the first form of the invention has free lift, whereas thetruck of the third form of the invention is without free lift.

In the first form of the invention, during upward movement of plunger 53from the Fig. 9 position to the Fig. 6 position, pin 73 is guided intohole 75 by the cooperative engagement between guides 71 and shaft 59 ofsheave 57. Upon further upward movement from the Fig. 6 position, theends of shaft 59 are moved out of guides 71. However, when the ram 53descends, the ends of shaft 59 will once again enter the guides 71because pin 73 and the fit of sheave 57 in slots 61 and 63 maintain thealignment between the ends of said shaft and said guides.

If the outerupright, in the elevated condition, should tend to stick, itwill be pulled downwardly by sheave 57 when the sheave moves downwardlysufliciently to engage the portions of the inner and outer uprightsdefining the bottom edges of slots 61 and 63.

Fig. 12 shows a modified form of the invention where the transversemembers of the load carriage are recessed at 300 to accommodate theupright structure. By this arrangement, a load on the carriage forks isdisposed closer to the front axle of the particular truck shown thanwithout such recessing. This is important because it decreases theforward tilting moment on the truck for a particular load. The uprightscannot be shifted farther rearwardly because of the presence of thedifferential housing 301 on the front axle. In some trucks thedifferential housings will be small enough to permit the uprights to bemounted sufliciently close to the front axle as to dispose the loadcarriage a minimum distance from the front axle without recessing theload carriage. This minimum distance is that where the load carriagejust clears the front tires. However, in other trucks,

the differential housings are sufliciently large to preventsuch minimumspacing unless the transverse load carriage members are recessed.

Recessing of such transverse load carriage members is permissible with atruck embodying the concepts of the present invention because the rearends of the load carriage plates 20 are joined by the shaft of roller117. Thus, when the carriage forks are loaded, the recessed portions ofthe carriage will be placed in compression, and the roller shaft intension. This is in contrast to the conventional carriage where thetransverse load carriage members are subjected to severe bendingstresses when the carriage is loaded, thus preventing recessing suchmembers.

The most important advantage of the lift truck of the present inventionis that the visibility of the driver has been remarkably increased ascompared to the visibility afforded by conventional lift trucks havinguprights formed of spaced-apart vertical members. Referring to Fig. 1,it is evident that the driver can readily see around or past the compactmast structure and observe the position of the forks relative to anyload which is to be picked up or deposited. Thus, the driver may pick upand deposit loads considerably faster than heretofore possible. Theexcellent visibility of the truck of the present invention also enablesthe operator to readily maneuver the truck down narrow or crowded aislesand thus increase the safe speed of travel of the truck over that atwhichhe would be required to operate a conventional truck.

It is also pointed out that merely mounting the load carriage to ridealong and be guided by the outer upright of the upright structure,instead of on the inner upright,

permits the width or lateral dimension of the uprightv structure to beconsiderably decreased over that of the conventional truck withoutincreasing the side wobble of the carriage relative to the upright onwhich it rides.

An important feature of the load elevating mechanism of the presentinvention is that the hydraulic ram. is not subjected to bending forcesmany of the forms of the invention. That is, in the first form of theinvention the load on chain 77, which tends to apply a bending force toplunger 53 to bend the plunger forwardly, as the parts are depicted inFig. 6, is taken by the cooperative engagement of the ends of the sheaveshaft 59 with guides 71, during elevation of the sheave from the Fig. 9position to the Fig. 6 position. In positions of higher ele vation, theguide pin 73 takes such force and prevents bending of the plunger 53. Inpractice, it has been found that. the application of any substantialbending force to the hydraulic ram results in improper operation becausesuch, force causes the cylinder to be deformed out of round, whichcauses objectionable leakage of the hydraulic fluid past the packingbetween the plunger and cylinder at the upper end of the cylinder.

Another advantage of. the lift truck of the present invention is thatthe hydraulic ram is substantially enclosed within the upright structureso that dirt and foreign matter will not readily be deposited on theplunger 53. Also, by enclosing the hydraulic ram, the ram is preventedfrom being bumped or struck during operation of the truck as sometimesoccurs in operating the conventional lift truck where the hydraulic ramis not protected but is exposed between the spaced, channel-shapeduprights. Although considerable advantage does not result from mountingthe ram within the uprights, it is possible to mount the ram outside ofthe uprights and still retain some of the visibility advantages of thetruck of the present invention.

A further advantage of the lift truck of the present invention is thathydraulic fluid which may from time to time leak out of the cylinder 51,between the packing arranged between the cylinder and plunger, willcollect within the lower end of the inner upright 35 instead of droppingon the floor or other surface on which the truck is being operated. Suchfluid may be periodically removed from the inner upright.

A further feature increasing the visibility of the driver of the lifttruck of the present invention is that the load chain 77 is arrangedwithin the lateral confines of the upright structure. This is incontrast to the conventional lift truck where the chains are arranged atthe sides of the hydraulic elevating ram and within the space betweenthe ram and the inner upright channels.

In the preferred forms of the invention, the tubular uprights have solidwalls, but the invention is not intended to be limited to solid walltubular members or columns. Thus, the words tubular and columnar aremeant to convey the idea of a member of tubular form or columnar form orconfiguration, rather than to convey the idea of only a solid wallstructure.

Another advantage of the upright structure of the present invention isthat it operates successfully under side loading stresses. In cottontopping, the truck is driven along a narrow aisle to the location of thebale to be removed. The aisle is usually too narrow to permit the truckto be turned to face the row of bales, so that the bale must be liftedby means of a boom on the uprights, with the truck facing along theaisle. Thus, the upright structure is subject to severe side loadingstresses. Since the conventional spaced uprights cannot be braced bydiagonal bracing, because the load carn'age rides between the inneruprights, these uprights would be excessively deformed by such a sideloading operation. However, the front and rear .walls of the uprights ofthe present invention efiectivelybrace the uprights against unduedeformation. Thus, the uprights of the present invention may besuccessfully. used inside loading operations. Also, because the frontand rear walls of the uprights of the present invention rigidly join theside walls to one another, the uprights are able to successfully resisttorsional stresses that would deform conventional uprights.

The concepts of the present invention have been shown as incorporated ina lift truck having two telescopically related uprights, but it isevident that the invention is not intended to be limited to a truckhaving two uprights since the concepts of the invention may beincorporated in a lift truck having more or less uprights.

Having described the invention in what are considered to be thepreferred embodiments thereof, it is desired that it be understood thatthe invention is not to be limited by the specific details shown unlessthey constitute critical features of the present invention, all of whichwill be'apparent by reference to the following claims.

I claim:

l. A lift truck having a single tubular mast at the front end thereof,said mast including inner and outer telescoped tubular uprights, eachupright having four sides and being rectangular in cross section, amount fixedly connected to the lower end of said inner upright andpivotally connected to said truck, means for tiltingsaid uprightsrelative to said truck, a load carriage, means mounting said carriage onsaid outer upright for movement therealong but preventing said carriagefrom turning about said outer upright, said mounting means includingguide elements engaging the four sides of said outer upright, powermeans separate from said uprights and operable independently of tiltingmovement thereof for elevating said load carriage along said outerupright and for elevating said outer upright relative to said innerupright, said power means including a vertical ram disposed within saidinner upright and having a part in fixed relation to said mount and apart movable upwardly when said ram is supplied with fluid underpressure, said inner upright being open at its upper end through whichsaid movable ram part is projected, flexible lift means connected at oneend to said carriage and secured at its opposite end in fixed relationto said mount, reeving means at the upper end of said outer upright overwhich said flexible lift means is trained, means providing a thrustconnection between said reeving means and said movable ram part, andmeans providing a thrust connection between said outer upright and saidmovable ram part upon upward movement of the latter.

2. A lift truck as defined in claim 1 in which said reeving means ismounted for rotation on the upper end of said outer upright, and inwhich the means which provides a thrust transmitting connection betweensaid outer upright and said movable ram part fixedly connects the upperend of said movable ram part to the upper end of said outer upright.

3. A lift truck as defined in claim 1 in which there are support membersfixedly connected to the upper end of said outer upright and rotatablysupport said reeving means, and in which the means which provides athrust transmitting connection between said outer upright and saidmovable ram part constitutes a connection between said movable ram partand the upper end of said outer upright.

4. A lift truck having a single tubular mast at the front end thereof,said mast including inner and outer telescoped tubular uprights, eachupright having four sides and being rectangular in cross section, amount fixedly connected to the lower end of said inner upright andpivotally connected to said truck, means for tilting said uprightsrelative to said truck, a load carriage, means mounting said carriage onsaid outer upright for movement therealong but preventing said carriagefrom turning about said outer upright, said mounting means includingguide elements engaging the four sides of said outer upright, powermeans separate from said uprights and operable independently of tiltingmovement thereof for elevating saidload carriage alongsaid outer uprightand for elevating said outer upright relative to said inner upright,said power means including a vertical ram disunduly posed within saidinnerupright and having a part in fixed relation to said mount and apart movable upwardly when said ram is supplied with fluid underpressure, said inner upright being open at its upper end through whichsaid movable ram part is projected, flexible lift means connected at oneend to said carriage and secured at its opposite end in fixed relationto said mount, reeving means at the upper end of said outer upright overwhich said flexible lift means is trained, the upper end of said rambeing connected to the upper end of said outer upright to provide athrust transmitting connection between said movable ram part and saidouter upright, means mounting said reeving means on the upper end ofsaid outer upright 80 that said movable ram part simultaneously raisesboth said outer upright and said reeving means.

5. An attachment for a lift truck comprising a tubular mast to bedisposed at the front end of the truck, said mast including inner andouter telescoped tubular uprights, each upright having four sides andbeing rectangular in cross section, a mount fixedly connected to thelower end of said inner upright and having means for pivotal connectionto the truck, means for tilting said uprights relative to said truck, aload carriage, means mounting said carriage on said outer upright formovement therealong but preventing said carriage from turning about saidouter upright, said mounting means including guide elements engaging thefour sides of said outer uprights, power means separate from saiduprights and operable independently of tilting movement thereof forelevating said load carriage along said outer upright and for elevatingsaid outer upright relative to said inner upright, said power meansincluding a vertical ram disposed within said inner upright and having apart in fixed relation to said mount and a part movable upwardly whensaid ram is supplied with fluid under pressure, said inner up rightbeing open at its upper end through which said movable ram part isprojected, flexible lift means connected at one end to said carriage andsecured at its opposite end in fixed relation to said mount, reevingmeans at the upper end of said outer upright over which said flexiblelift means is trained, means providing a thrust connection between saidreeving means and said movable ram part, and means providing a thrustconnection between said outer upright and said movable ram part uponupward movement of the latter.

6. A lift truck having a single tubular mast at the front end thereof,said mast including inner and outer telescoped tubular uprights, eachupright having four sides and being rectangular in cross section, meansproviding a pivotal connection between the lower end of said innerupright and said truck, means for tilting said uprights relative to saidtruck, a load carriage, means mounting said carriage on said outerupright for movement therealong but preventing said carriage fromturning about said outer upright, said mounting means including guideelements engaging the four sides of said outer upright, power meansseparate from said uprights and operable independently of tiltingmovement thereof for ele-' vating said load carriage along said outerupright and for elevating said outer upright relative to said innerupright, said power means including a vertical ram disposed within saidinner upright and having a part in fixed relation to said mount and apart movable upwardly when said ram is supplied with fluid underpressure, said inner ,upright being open at its upper end through whichsaid movable ram part is projected, flexible lift means connected at oneend to said carriage and secured at its opposite end in fixed relationto said inner upright, reeving means at the upper end of said outerupright over which said flexible lift means is trained, means providinga thrust connection between said reeving means and said movable rampart, and means providing a thrust connection between said outer uprightand said movable ram part upon upward movement of the latter.

7. A lift'truck as set forth in claim 6 in which said reeving means ismounted for rotation on the upper end of said outer upright, and inwhich the means which provides a thrust transmitting connection betweensaid outer upright and said movable ram part fixedly connects the upperend of said movable ram part to the upper end of said outer upright.

8. A lift truck as set forth in claim 6 in which the upper end of saidram is connected to the upper end of said outer upright to provide athrust transmitting connection between said movable ram part and saidouter upright, and in which there are means mounting said reeving meanson the upper end of said outer upright so that said movable ram partsimultaneously raises both said outer upright and said reeving means.

9. A lift truck having a mast structure at the front end thereof, saidmast structure having a single tubular mast, said mast including innerand outer tubular uprights in telescopic relation with respect to oneanother, each upright having four sides and being quadrangular in crosssection, said mast structure including a mount fixedly connected to thelower end of said inner upright and pivotally connected to said truck,means for tilting said uprights relative to said truck, a load carriage,means mounting said carriage on said outer upright for movementtherealong but preventing said carriage from turning about said outerupright, said mounting means including guide elements engaging the foursidesof said outer upright, power means separate from said uprights andoperable independently of tilting movement thereof for elevating saidload carriage along said outer upright and for elevating said outerupright relative to said inner upright, said power means including avertical ram disposed within said inner upright, said ram havingrelatively movable, vertically extensible parts including a part infixed relation to said mount, said ram having a retracted position inwhich it is contained with said inner upright, means to conduct fluidunder pressure to said ram to cause extension of said ram and cause apart thereof to be projected upwardly, said inner upright being formedwith an opening at its upper end through which the last mentioned partis projected, flexible lift means connected at one end to said carriage,reeving means at the upper end of said outer upright over which saidflexible lift means is trained, the upper end of said ram beingconnected to the upper end of said outer upright to provide for upwardmovement of said outer upright during extension of said ram, saidreeving means being mounted on said outer upright at the upper end Ithereof to provide for simultaneous upward movement of said reevingmeans and said outer upright during extension of said ram, and meansanchoring the other end of said flexible lift means to said ram at aplace to multiply the extensible ram movement that causes carriagemovement.

10. A lift truck having a mast structure at the front end thereof, saidmast structure having a single tubular mast, said mast including firstand second tubular uprights in telescopic relation with respect to oneanother, with the second upright surrounding the first upright, eachupright having four sides and being quadrangular in cross section, saidmast structure including a mount fixedly connected to the lower end ofsaid first upright and pivotally connected to said truck, means fortilting said uprights relative to said truck, a load carrying structure,means mounting said load carrying structure on said second upright formovement therealong but preventing said carrying structure from turningabout said second upright, said mounting means including guide elementsengaging the four sides of said second upright, power means separatefrom said uprights and operable independently of tilting movementthereof for elevating said load carrying structure along said secondupright and for elevating said second upright relative to said firstupright, said power means including a vertical ram disposed within saidfirst upright, said ram having relatively movable, vertically extensibleparts including a part in fixed relation to said mount, said ram havinga retracted position in which it is contained within said first upright,means to conduct fluid under pressure to said ram to'cause extensionofsaid ram and cause a part thereof to be projected upwardly, said firstupright being formed with an opening at its upper end through which thelast mentioned part is projected, flexible lift means connected at oneend to said carrying structure, reeving means at the upper end of saidsecond upright over which said flexible lift means is trained, the upperend of said ram being connected to the upper end of said second uprightto provide for upward movement of said second upright during extensionof said ram, said reeving means being mounted on said second upright atthe upper end thereof to provide for simultaneous upward movement ofsaid reeving means and said'second upright during extension of said ram,and means anchoring the other end of said flexible lift means to saidram at a place to multiply the extensible ram movement that causescarrying structure movement.-

UNITED STATES PATENTS 1,705,145 Thrift Mar. 12, 1929 1,789,025 ShepardIan. 13, 1931 1,860,222 Billings May 24, 1932 2,456,320 Repke Dec. 14,1948 2,465,796 Freeman Mar. 29, 1949 2,503,180 Wagner Apr. 4, 19502,569,126 Daniels Sept. 25, 1951 2,642,157 Milz June 16, 1953 2,648,401Frischmann Aug. 11, 1953 2,705,572 Rush Apr. 5, 1955 2,745,612 IZ-"---l-. -P- May .2,.

